1. Field of the Invention
The present invention relates to a nonvolatile magnetic memory and a magnetic random access memory that are low-power consuming and highly reliable.
2. Background Art
Magnetic random access memory is gaining attention as a nonvolatile memory that has the potential to realize a “universal memory,” which combines the attributes of high integration, high access speed, and low power consumption. A magnetic random access memory comprises a magnetic memory cell consisting of a tunneling magnetoresistive element having Al or Mg oxide in an insulation film (T. Miyazaki and N. Tezuka, J. Magn. Magn. Mater. 139, L231 (1995); and S. Yuasa et al., Nature Material 3, 868 (2004)), and a transistor for selecting the magnetic memory cell. Information is read via the output voltage of the tunneling magnetoresistive element. Conventionally, information is written by applying a voltage to a bit line and a word line to produce a current-induced spatial magnetic field, with which the magnetization direction of the ferromagnetic free layer of the tunneling magnetoresistive element. As the magnetic memory cells become increasingly finer due to increases in the level of integration, the volume of the ferromagnetic free layer decreases, resulting in an increase in the magnetic field required for magnetization reversal. As a result, more current is required for writing and power consumption increases. In another information writing method, current is caused to flow through the tunneling magnetoresistive element so as to rotate magnetization. This is the so-called spin-transfer torque magnetization reversal method, which is synonymous with the spin-injection magnetization reversal method, which is disclosed in U.S. Pat. No. 5,695,864 and JP Patent Publication (Kokai) No. 2002-305337 A, for example. Such write method, as opposed to the aforementioned method involving the spatial magnetic field, is capable of reducing the current required for writing even when the size of the ferromagnetic free layer of a tunneling magnetoresistive element becomes increasingly finer due to increases in integration. Thus, this write method is advantageous for reduction of power consumption.